I'd only say that laptops are reusable within the organization, so if the data was eliminated from that, it would be because the laptop would be redeployed to another individual within the organization, rather than declare it surplus. So is it unusual? No. Is it unusual in this case? I guess you'd have to decide whether eliminating valuable information from a laptop is eliminating evidence. Normally, what we do is back up the drives. In other words, there should be some discs on the file containing all the e-mails and all the information as they pertain to that investigation, because in essence you may be eliminating crucial evidence that could be used at a future date.
On April 30th, 2007. See this statement in context.